Acoustical panel with cellular lattice embedded into sound absorptive element



CELLULAR LATTICE EMBEDDED D ABSORPTIVE ELEME Filed June 1, 196

Nov. 7, 1951 ACOUSTICAL PA J v INTO SOU Original JIIIIIIITI.

ATTQRNEYS v vided and this 4 Claims. (Cl. 181-33) This invention relatesto the art of acoustical panels, more particularly to an improvedacoustical panel in which the sound deadening properties are subject toselective variation by the designer, and in which the exposed surface ofthe panel may have any of a variety of desired decorative arrangementsor coverings formed thereon without interfering with the sound deadeningproperties of the panel.

This application is a division of copending application Ser. No.371,310, filed June 1, 1964, now abandoned.

As conducive to an understanding of the invention, it is noted that avariety of different types of acoustical panels have been evolved foruse on walls, ceilings, floors, or the like partitioning structuresemployed to enclose any area in which it would be desirable to deaden ordissipate noise in the enclosed area. The sound absorptive properties ofa material are generally dependent on the porosity and internalstructure of the material, whereby the sound to be deadened is trappedwithin the pores of 'the material, and the vibrational energy of thesound dissipated by the flexing of the material. It is, however, foundthat the use of these sound deadening materials in fabricatingacoustical panels produces a relatively soft surface panel subject tomarrin-g, and of such structural weakness as to become distortedwithtime. Additionally, the porous nature of conventional sound absorbingmaterials tends to accumulate dirt, and any attempts to paint or cleanthe exposed surfaces of these acoustical panels either clogs the poresthereof with resultant elimination of the sound deadening properties, orproduces further deterioration of the panel.

It is accordingly among the objects of the invention to provide animproved acoustical panel having an exposed surface subject to readycleaning or other maintenance procedures.

Another object of the invention is to provide an improved acousticalpanel With an exposed surface which may be painted or otherwise treatedwithout interfering with the sound deadening properties of the panel.

A further object of the invention is to provide an acoustical panel withimproved means for trapping sound in proximity to the sound deadeningmaterial of the panel.

Another object of the invention is to provide an improved sounddeadening panel having a relatively strong exposed surface in which therigidity and strength of the surface does not produce undesiredreflection of the sound waves impinging thereon.

According to the invention, an improved acoustical tile embodying theinstant invention is formed by means of a sound absorptive element suchas conventionally available intercellular or fibrous board. Celluloseboards, mineral fi ber boards, fiberglass, or rockwool may readily beemployed. Arranged over the surface of the sound absorptive elementwhich is normally intended for positioning in sound receiving positionwith respect to the area in which sound is to be deadened, is a cellularlattice. This lattice may be fabricated of any one of a large variety ofmaterials such as paper, sheet metal, plastic or the like. Expandedpaper board is found particularly suitable. The lattice defines aplurality of cells adjacent 3,351,154 Patented Nov. 7, 1967 the soundreceiving surface of the sound absorptive element. A perforate coveringsheet formed of any one of a large variety of suitable sheet materialsuch as sheet steel, sheet plastic, or. the like is secured over thelattice with the perforations of the covering sheet permittingtransmission of sound through said sheet to the cells defined by thelattice. The covering sheet is selected from that class of materialssubject to ready cleaning, painting, or the provision of desireddecorative motifs thereon.

A feature of the invention resides in the sound trapping properties ofthe lattice which acts to form a resonator trapping the sound inproximity to the sound absorp tive element to insure damping of thesound.

In the accompanying drawings in which are shown one or more of variouspossible embodiments of the several features of the invention.

FIG. 1 is a schematic cross sectional view through a room or the likearea showing the novel acoustical panel employed asia ceiling tile,

7 FIG. 2 is a perspective view with parts 'broken away of an acousticalpanel made in accordance with the teachings of this invention and on alarger scale,

FIG. 3 is a cross sectional view taken on line 3-3 of FIG. 2 showing thedetails of the structural components of the panel,

FIG. 4 is a fragmentary detail sectional view showing an acousticalpanel made in accordance with the teachings of this invention in whichthe edges of the covering panel are turned up to enclose the lattice andsound absorbing board to provide acleanjoint between panels,

The density, and thickness of the sound absorptive element is selected,dependent on the sound absorptive qualities desired, and production andhandling considerations. 3

In the illustrative embodiment of the invention, only the un'dersurface12 of the board 11 is shown as intended for sound impingement thereon.To this sound impinging sur face 12 is secured a lattice 13, the wall ofwhich defines a plurality of cells 14. The lattice 13 may be fabricatedin a variety of ways of a large variety of materials. Thus, paper board,sheet plastic, molded plastics, or molded fiber board, or the materialemployed for the'sound absorptive element itself may be employed infabricating the lattice.

By way of example, it is found that expanded paper board stock arrangedin the illustrated honeycomb lattice may be satisfactorily employed.This paper board stock lattice 13 is secured to the sound impingingsurface of the sound absorbing board 11 by the use of glue or the likeadhesives.

It has further been found that better structural proper ties areobtained by forcing the edge of the lattice 13 into the sound absorptiveboard 11 as shown in FIG. 3.

Arranged over the lattice 13 to sandwich the lattice between itself andthe sound absorbing board 11 is a covering plate 15 formed with aplurality of spaced perforations 16. Covering plate 15 is formed of arelatively rigid sheet material such as sheet plastic, or any one ofthat class of materials having desired structural rigidity. Sheet steelis found particularly suitable. The perforations 16 are spaced so as toinsure the free passage. of air through the covering plate 15 to thecells 14 defined by the walls of lattice 13. The materials of which thecovering plate are formed are selected from a class of material subjectto ready maintenance, ready cleaning and having desired texturessuitable for use in the .areas in which the plate is employed. Coveringplate 15 is secured to the lattice 'by utilization of conventionalfastening techniques. Thus, when expanded paper board is employed forforming the lattice, paper bonding adhesives have been foundparticularly suitable.

Alternatively, it will be understood by those skilled in the art thatthe covering plate and lattice may be integrally molded of materialssuch as metal, plastic or the like within the scope of the invention.

In the FIG. 4 embodiment of the invention, the panel board 410 is shownas formed to provide a plurality of discreet panel sections. The panelboard 410 is substantially identical to the panel board as illustratedin FIGS. 2 and 3. However, the configuration of the covering plate ismade such as to provide this covering plate 15 with a plurality ofupturned peripheral edges 416 which serve to define a discreet panel,and implement the installation of the panels to provide a clean straightjoint between abutting panels.

As shown illustratively in FIG. 5, the rear surface of the panel 10, onthat face of the sound absorptive boar-d 11 observe to the soundimpinging undersurface 12 thereof, as illustrated, will be formed with asound transmission loss coating 50 such as vinyl, enamel, or the likecoating materials providing a relatively impervious surface.

In use, the afore-described panel board may be made of any suitabledimensions. Where formed of the conventional rectangular panels, thesepanels are arranged to cover the area which it is intended to providewith desired sound deadening properties. Thus, as best shown in FIG. 1,the panels '10 are shown as arranged to provide sound deadening ceilingtiles. The ceiling tiles 10 are shown suspended by supporting channels Cdepending from hangers H in conventional fashion.

It is thus seen that a simple effective sound deadening panel has beenprovided in which desired sound deadening properties are obtained byutilization of the conventional sound absorptive materials. However, thesound absorptive materials have their sound deadening propertiesenhanced by the provision of resonating cells which serve to trap thesound to be deadened in proximity to the sound absorptive surface, andthe exposed covering panel =15 is formed of a material which serves thetwo-fold function of providing a surface to reflect the sound entrappedwithin the cells back to the sound deadening surface, and additionallyprovides a surface of sufiicient rigidity to implement the formation ofdesired decorative finishes and permits the ready cleaning of the wallor ceiling panel.

The size and number of the perforations per cell of lattice and the sizeand depth of the cells of the lattice may be varied to obtain resonanceat any required frequency. The sound absorptive properties of the soundabsorptive board may be selected to provide an optimum degree of dampingin the specific cell of the lattice. Various different facingperforation patterns and lattice cell size can be used to broaden thefrequency range of the resonator should this be desired. Furthermore,the resistance of the perforated metal facing may be increased by theintroduction of a thin, porous fabric 51, such as thin gauze or paperbetween the perforated metal and the lattice cells.

As many changes could be made in the above constructions, and manyapparently widely different embodiments of this invention could be madewithout departing from the scope of the claims, it is intended that allmatter contained in the above description or shown in the accompanyingdrawings shall be interpreted as illustrative and not in a limitingsense.

Having thus described my invention, what 1 claim as new and desire tosecure by Letters Patent of the United States is:

1. An'acoustical panel comprising a sound absorptive element having asurface adapted for arrangement in sound receiving position with respectto any area in which sound is to be deadened, a cellular latticepositioned over the sound receiving surface of said sound absorptiveelement, said lattice defining a plurality of cells, an edge of saidcellular lattice adjacent said sound absorptive element being embeddedinto said sound asborptive element, and a perforate rigid covering platearranged over the surface of said lattice opposed to the soundabsorptive element and secured to said lattice, the perforation of saidcovering plate permitting transmission of sound through said plate tothe cells defined by said lattice.

2. The combination set forth in claim 1 in which said covering plate hasits peripheral edge turned inwardly so as to encompass the edges of thesound absorptive element.

3. The combination set forth in claim 1 in which said sound absorptiveelement has the surface thereof remote from the lattice, coated with arelatively impervious coating to seal said surface.

4. The combination set forth in claim 1 in which a sheet of thin porousmaterial is interposed between the covering plate and the lattice.

References Cited UNITED STATES PATENTS 2,148,496 2/1939 Park 18133.12,271,929 2/1942 Venzie 181--33.1 3,043,730 7/1962 Adie 18l33.13,111,188 11/1963 Rees et al 181-33.1

FOREIGN PATENTS 206,535 4/ 1956 Australia. 723,621 2/1955 Great Britain.

RICHARD B. WILKINSON, Primary Examiner.

R. S. WARD, Examiner.

1. AN ACOUSTICAL PANEL COMPRISING A SOUND ABSORPTIVE ELEMENT HAVING ASURFACE ADAPTED FOR ARRANGEMENT IN SOUND RECEIVING POSITION WITH RESPECTTO ANY AREA IN WHICH SOUND IS TO BE DEADENED, CELLULAR LATTICEPOSITIONED OVER THE SOUND RECEIVING SURFACE OF SAID SOUND ABSORPTIVEELEMENT, SAID LATTICE DEFINING A PLURALITY OF CELLS, AN EDGE OF SAIDCELLULAR LATTIVE ADJACENT SAID SOUND ABSORPTIVE ELEMENT BEING EMBEDDEDINTO SAID SOUND ASBORPTIVE ELEMENT, AND A PERFORATE RIGID COVERING PLATEARRANGED OVER THE SURFACE OF SAID LATTIVE OPPOSED TO THE SOUNDABSORPTIVE ELEMENT AND SECURED TO SAID LATTIVE, THE PERFORATION OF SAIDCOVERING PLATE PERMITTING TRANSMISSON OF SOUND THROUGH SAID PLATE TO THECELLS DEFINED BY SAID LATTICE.